JP2008141107A - Method for manufacturing ferroelectric element - Google Patents

Abstract

A method of manufacturing a ferroelectric capacitor that is driven at a low voltage is provided.
A method of manufacturing a ferroelectric element 100 includes a step of sequentially forming a TiAlN film 12, a first iridium film 22, an iridium oxide film 24, and a platinum film 26 above a substrate 10, and PZT, PZTN, The surface of the ferroelectric film 30 is formed by using a step of forming a ferroelectric film 30 such as SBT and an organic liquid such as ozone or an alcohol or amine that has a pKa> 7 and does not contain a metal element. A step of cleaning, a step of heat treatment for crystallizing the ferroelectric film 30, and a step of forming a metal layer 40 of the iridium oxide film 44 and the iridium film 46 on the ferroelectric film 30. Including.
[Selection] Figure 1

Description

  The present invention relates to a method for manufacturing a ferroelectric element.

  The ferroelectric material covers that it is used as an element of a capacitor structure sandwiched between an upper electrode and a lower electrode. The ferroelectric element can be applied to a ferroelectric memory, a piezoelectric element, or the like. Driving such a ferroelectric element at a low voltage is extremely important, and various developments have been made for this purpose. For example, Japanese Unexamined Patent Application Publication No. 2004-214274 discloses that low voltage driving is realized by controlling the orientation of a ferroelectric film to align the polarization axis direction.

In order to enable low voltage driving, it is necessary to keep the interface between the ferroelectric and the electrode clean. That is, if the interface between the ferroelectric and the electrode cannot be cleaned, the interface layer becomes a series capacitor component, and an offset is applied to the driving voltage, which hinders low voltage driving. In particular, when a ferroelectric film is formed by a liquid phase method or a gas phase method, an interface layer containing a carbon residue is easily formed on the surface, and such an interface layer is not sufficiently crystallized. It tends to be a low dielectric constant layer.
JP 2004-214274 A

  An object of the present invention is to provide a method of manufacturing a ferroelectric element that can keep the interface between a ferroelectric and an electrode clean.

A method for manufacturing a ferroelectric element according to the present invention includes:
(A) forming a ferroelectric film above the substrate;
(B) cleaning the surface of the ferroelectric film using ozone or an organic liquid that has a pKa> 7 and does not contain a metal element;
(C) forming a metal layer above the ferroelectric film;
including.

  In the present invention, when a specific B member (hereinafter referred to as “B member”) provided above a specific A member (hereinafter referred to as “A member”), the B member is directly on the A member. The meaning includes the case where it is provided and the case where the B member is provided on the A member via another member.

  According to the manufacturing method of the present invention, the interface between the ferroelectric film and the electrode can be kept clean without adversely affecting the ferroelectric film. Therefore, a ferroelectric element that can be driven at a low voltage can be provided.

In the method for manufacturing a ferroelectric element according to the present invention,
A step of performing a heat treatment for crystallizing the ferroelectric film may be further included between the steps (b) and (c).

In the method for manufacturing a ferroelectric element according to the present invention,
Between the step of performing the heat treatment and the step (c),
The method may further include a step of cleaning the surface of the ferroelectric film using ozone or an organic liquid that has pKa> 7 and does not include a metal element.

In the method for manufacturing a ferroelectric element according to the present invention,
Between the steps (a) and (b),
The method may further include a step of performing a heat treatment for degreasing the ferroelectric film.

In the method for manufacturing a ferroelectric element according to the present invention,
The organic liquid may be a liquid containing alcohols.

In the method for manufacturing a ferroelectric element according to the present invention,
The organic liquid may include an alcohol having 4 or more carbon atoms.

In the method for manufacturing a ferroelectric element according to the present invention,
The organic liquid may include butanol or octanol.

In the method for manufacturing a ferroelectric element according to the present invention,
The organic liquid may be a liquid containing amines.

In the method for manufacturing a ferroelectric element according to the present invention,
In the step (b), the surface of the ferroelectric film can be cleaned using ozone water.

A method for manufacturing a ferroelectric element according to the present invention includes:
Forming a first electrode above the substrate;
Forming a ferroelectric film above the lower electrode;
Applying a heat treatment for degreasing the ferroelectric film;
Cleaning the surface of the ferroelectric film with ozone water, butanol or octanol;
Applying a heat treatment for crystallizing the ferroelectric film;
Forming an upper electrode above the ferroelectric film;
including.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings.

1. Ferroelectric element In this embodiment, a case where a ferroelectric capacitor is applied as an example of a ferroelectric element will be described.

  FIG. 1 is a cross-sectional view schematically showing a ferroelectric capacitor 100 of the present embodiment. The ferroelectric capacitor 100 includes a TiAlN film 12, a first electrode 20, a ferroelectric film 30, and a second electrode 40 that are formed on the base 10 and are sequentially formed from the base 10 side. The first electrode 20 includes a first iridium film 22, a first iridium oxide film 24, and a first platinum film 26 that are sequentially formed from the substrate 10 side. The second electrode 40 includes a second platinum film 42, a second iridium oxide film 44, and a second iridium film 46, which are sequentially formed from the ferroelectric film 30 side.

The base 10 includes a substrate. Examples of the substrate include elemental semiconductors such as silicon and germanium, semiconductor substrates such as compound semiconductors such as GaAs and ZnSe, metal substrates such as Pt, sapphire substrates, MgO, SrTiO ₃ , BaTiO ₃ , and insulating substrates such as glass. . The substrate 10 may include one or more transistors on the substrate. The transistor includes an impurity region serving as a source region or a drain region, a gate insulating layer, and a gate electrode. An element isolation region may be formed between the transistors, thereby achieving electrical insulation between the transistors.

  The TiAlN film 12 is formed on the expectation 10. The TiAlN film 12 is made of titanium and aluminum nitride (TiAlN) and has an oxygen barrier function. The TiAlN film 12 has a face-centered cubic crystal structure, and is preferentially oriented, for example, in the (111) plane or the (200) plane. Here, the “priority orientation” means a state where the diffraction peak intensity from the (111) plane or the (200) plane is larger than the diffraction peaks from other crystal planes in the θ-2θ scan of the X-ray diffraction method.

  The first iridium film 22 is formed on the TiAlN film 12, and the first iridium oxide film 24 is formed on the first iridium film 22. The first iridium film 22 and the first iridium oxide film 24 are preferably preferentially oriented in the (111) plane.

  The first platinum film 26 is formed on the first iridium oxide film 24. The first platinum film 26 is preferentially oriented in the (111) plane. Thereby, the ferroelectric film 30 formed thereon is easily preferentially oriented in the (111) plane.

  The first electrode 20 may have all of the above-described films, or may be only the first platinum film 26, or the first platinum film 26 and the first iridium film 22 or The first iridium oxide film 24 may be used.

The ferroelectric film 30 is formed on the first electrode 20, that is, on the first platinum film 26. As the material of the ferroelectric film 30, a known ferroelectric material is used. For example, the ferroelectric film 30 can be made of a perovskite oxide represented by a general formula ABO ₃ , where A includes Pb, B includes Zr and At least one of Ti can be included. The B may further contain niobium (Nb), for example. Specifically, as the ferroelectric film 30, for example, lead zirconate titanate (Pb (Zr, Ti) O ₃ : PZT), lead titanate (PbTiO ₃ ), lead zirconate titanate niobate (Pb) (Zr, Ti, Nb) O ₃ ) (hereinafter also referred to as “PZTN”) or the like can be used. PZTN is a ferroelectric material obtained by adding Nb to PZT.

Further, A in the general formula ABO ₃ can include, for example, Bi, La, Sr, Ca, and Ba in addition to Pb. These elements can be contained in the A site at a ratio of 20% or less, for example. In addition, Si can be added to the perovskite oxide represented by the general formula ABO ₃ . The ferroelectric film 30 can be preferentially oriented in the (111) plane in order to extract good polarization characteristics.

Further, as the ferroelectric film 30, for example, SrBi ₂ Ta ₂ O ₉ (SBT) can be used. At least one of Si and Nb can be added to SBT.

  The second platinum film 42, the second iridium oxide film 44, and the second iridium film 46 constituting the second electrode 40 are respectively the first platinum film 26, the first iridium oxide film 24, the second Since the material is the same as that of the iridium film 1 of FIG.

  The second electrode 40 may include all of the above-described films, or may be only the second platinum film 42, or the second platinum film 42 and the second iridium film 46 or The second iridium oxide film 44 may be used.

  The configuration of the ferroelectric element according to the present embodiment is as described above.

2. Method for Manufacturing Ferroelectric Element First, the substrate 10 is formed, and a TiAlN film 12, a first iridium film 22, a first iridium oxide film 24, and a first platinum film 26 are formed thereon in that order.

  Examples of the method for forming the TiAlN film 12 include a sputtering method and a CVD method. For example, when the film is formed by sputtering, the TiAlN film 12 is formed on the (200) plane or (111) by adjusting the amount of nitrogen in the mixed gas using a mixed gas of argon and nitrogen as a process gas. ) Surface can be preferentially oriented.

  A method for forming the first iridium film 22 and the first iridium oxide film 24 can be appropriately selected depending on the material, but for example, chemical vapor deposition in addition to sputtering and vacuum deposition. The method (CVD) can be applied. As a method for forming the first platinum film 26, a sputtering method, a vacuum evaporation method, or the like can be used.

  As a result, the first electrode 20 composed of the first iridium film 22, the first iridium oxide film 24, and the first platinum film 26 is formed.

  Next, a ferroelectric film 30 is formed on the first electrode 20. A method for forming the ferroelectric film 30 can be selected as appropriate according to the material used. For example, a solution coating method (including a sol-gel method and a MOD method), a sputtering method, a CVD method, and a MOCVD method are used. Laws can be applied. Specifically, a precursor that is in a state before the ferroelectric film 30 is crystallized is formed.

Next, heat treatment for degreasing the ferroelectric film 30 is performed. In this degreasing step, the organic components remaining in the precursor layer can be thermally decomposed into NO ₂ , CO ₂ , H ₂ O, and the like and separated. The temperature of this heat treatment step can be, for example, about 300 degrees.

  Next, the surface of the ferroelectric film 30 is cleaned. As the cleaning liquid, ozone water or a predetermined organic liquid is used. The ozone concentration of ozone water can be selected as appropriate, and can be, for example, 50 ppm or more. The predetermined organic liquid is an organic liquid that has pKa> 7 and does not contain a metal element, and specifically, can be alcohols, amines, and the like. The alcohols preferably have 4 or more carbon atoms, such as n-butanol and n-octanol. The amines preferably have 4 or more carbon atoms, such as butylamine and triethylamine.

  Next, a heat treatment for crystallizing the ferroelectric film 30 is performed. Thereby, the precursor of the ferroelectric film 30 can be crystallized by heating. The temperature of this heat treatment step can be, for example, 600 degrees to 700 degrees. The apparatus used for the heat treatment step is not particularly limited, but can be, for example, an RTA (Rapid Thermal Annealing) apparatus.

Next, the second electrode 40 is formed on the ferroelectric film 30. Specifically, the second platinum film 42, the second iridium oxide film 44, and the second iridium film 46 are formed in this order. In the present embodiment, the second electrode 40 includes a second platinum film 42, a second iridium oxide film 44, and a second iridium film 46, and the first iridium film 22 described above, The first iridium oxide film 24 and the first platinum film 26 are formed using the same materials. As a film formation method, a film formation method similar to that of the first electrode 20 described above can be used. The second electrode 40 is not limited to the above-described one, and for example, a noble metal such as Pt or Ir or an oxide thereof (for example, IrO _x ) can be used as a material. The second electrode 40 may be a single layer of these materials or a multilayer structure in which layers made of a plurality of materials are stacked. Thereafter, patterning is performed by a known photolithography and etching technique.

  The ferroelectric capacitor 100 can be manufactured through the above steps. In the method for manufacturing a ferroelectric capacitor according to the present embodiment, the surface of the ferroelectric film 30 is cleaned with ozone water or a predetermined organic liquid after the ferroelectric film 30 is formed. Since ozone water or a predetermined organic liquid has a property of dissolving a carbon compound, the carbon residue generated in the film forming process of the ferroelectric film 30 can be removed by this cleaning.

  In particular, in this embodiment, the cleaning is performed before the heat treatment step for crystallization of the ferroelectric film 30. Thereby, since it can wash | clean before a carbon residue crystallizes, a carbon residue can be removed reliably by a shorter time washing | cleaning.

  In addition, by cleaning with ozone water or a predetermined organic liquid, the ferroelectric film 30 can be prevented from being reduced during the cleaning process. Further, when the ferroelectric film 30 is made of a ferroelectric material that dissolves in an acid, the ferroelectric film 30 is dissolved in the cleaning liquid by using ozone water or an organic liquid of pKa> 7. Can be prevented.

3. Modification 3.1. First Modified Example Next, a method for manufacturing a ferroelectric capacitor according to a first modified example will be described. In the ferroelectric capacitor manufacturing method according to the present embodiment described above, the surface of the ferroelectric film 30 is cleaned before the heat treatment step for crystallizing the ferroelectric film 30. In the ferroelectric capacitor manufacturing method according to the first modification, the surface of the ferroelectric film 30 is cleaned after the heat treatment step. The details of the cleaning process and the other manufacturing processes are the same as the above-described cleaning process, and thus the description thereof is omitted.

3.2. Second Modification Next, a method for manufacturing a ferroelectric capacitor according to a second modification will be described. In the method for manufacturing a ferroelectric capacitor according to the above-described embodiment, the surface of the ferroelectric film 30 is cleaned before the heat treatment step for crystallizing the ferroelectric film 30. In the ferroelectric capacitor manufacturing method according to the second modification, the surface of the ferroelectric film 30 is cleaned both before and after the heat treatment step. Thereby, a carbon residue can be removed reliably. The details of the cleaning process and other manufacturing processes are the same as the above-described cleaning process, and thus the description thereof is omitted.

4). Experimental Example Next, an experimental example according to the present embodiment will be described.

4.1. Experimental Examples 1-3
The manufacturing method of the ferroelectric capacitor according to Experimental Examples 1 to 3 is as follows.

  First, the surface of the silicon substrate was thermally oxidized to form a silicon oxide film having a thickness of 400 nm. Next, a 100 nm thick TiAlN film was formed on the silicon oxide film by RF sputtering. Next, an iridium film with a thickness of 100 nm and an iridium oxide film with a thickness of 30 nm were formed on the TiAlN film by DC sputtering. Next, a first platinum film having a thickness of 100 nm was formed on the iridium oxide film by an evaporation method.

Next, a PbZr _0.15 Ti _0.70 Nb _0.15 O ₃ (hereinafter referred to as PZTN) precursor film is formed on the first platinum film by spin coating, and degreased at 300 ° C. to form an amorphous material. A PZTN film was formed.

  Next, the PZTN surface was cleaned using a predetermined cleaning solution. The types of the predetermined cleaning liquid are as shown in Table 1 below.

  Next, crystallization was performed by lamp heating at 650 ° C. for 5 minutes to form a PZTN film layer having a thickness of 100 nm.

  Next, a second platinum film having a thickness of 100 nm was formed on the PZTN film by DC sputtering using a metal mask. Next, the PZTN film was recovered by lamp heating at 650 ° C. for 5 minutes.

  A ferroelectric capacitor was manufactured by the above process.

4.2. Experimental Examples 4-6
The manufacturing method of the ferroelectric capacitor according to Experimental Examples 4 to 6 is as follows.

  First, the surface of the silicon substrate was thermally oxidized to form a silicon oxide film having a thickness of 400 nm. Next, a 100 nm thick TiAlN film was formed on the silicon oxide film by RF sputtering. Next, an iridium film with a thickness of 100 nm and an iridium oxide film with a thickness of 30 nm were formed on the TiAlN film by DC sputtering. Next, a first platinum film having a thickness of 100 nm was formed on the iridium oxide film by an evaporation method.

Next, a PbZr _0.15 Ti _0.70 Nb _0.15 O ₃ (hereinafter referred to as PZTN) precursor film is formed on the first platinum film by spin coating, and degreased at 300 ° C. to form an amorphous material. A PZTN film was formed.

  Next, crystallization was performed by lamp heating at 650 ° C. for 5 minutes to form a PZTN film layer having a thickness of 100 nm.

  Next, the PZTN surface was cleaned using a predetermined cleaning solution. The types of the predetermined cleaning liquid are as shown in Table 1 below.

  Next, a second platinum film having a thickness of 100 nm was formed on the PZTN film by DC sputtering using a metal mask. Next, the PZTN film was recovered by lamp heating at 650 ° C. for 5 minutes.

  A ferroelectric capacitor was manufactured by the above process.

4.3. Experimental Example 7
The manufacturing method of the ferroelectric capacitor according to Experimental Example 7 is as follows.

  First, the surface of the silicon substrate was thermally oxidized to form a silicon oxide film having a thickness of 400 nm. Next, a 100 nm thick TiAlN film was formed on the silicon oxide film by RF sputtering. Next, an iridium film with a thickness of 100 nm and an iridium oxide film with a thickness of 30 nm were formed on the TiAlN film by DC sputtering. Next, a first platinum film having a thickness of 100 nm was formed on the iridium oxide film by an evaporation method.

Next, a PbZr _0.15 Ti _0.70 Nb _0.15 O ₃ (hereinafter referred to as PZTN) precursor film is formed on the first platinum film by spin coating, and degreased at 300 ° C. to form an amorphous material. A PZTN film was formed.

  Next, crystallization was performed by lamp heating at 650 ° C. for 5 minutes to form a PZTN film layer having a thickness of 100 nm.

  Next, a second platinum film having a thickness of 100 nm was formed on the PZTN film by DC sputtering using a metal mask. Next, the PZTN film was recovered by lamp heating at 650 ° C. for 5 minutes.

  A ferroelectric capacitor was manufactured by the above process.

4.4. Evaluation 1
The ferroelectric films obtained in Experimental Examples 1 to 7 were evaluated. The evaluation was performed on the saturation characteristic of the remanent polarization value of the ferroelectric capacitor. Table 1 shows an outline of the results of the types and the saturation characteristics of the cleaning solutions used in Experimental Examples 1 to 7. In the property column of Table 1, ◎ indicates that the property was the best, ○ indicates that the property was good, △ indicates the property as a reference, and x indicates the property is below the reference. Indicate.

  FIG. 2 is a diagram showing the saturation of the remanent polarization value of a ferroelectric capacitor manufactured using n-butanol as the cleaning liquid. In FIG. 2, the horizontal axis is the applied voltage value, and the vertical axis is the normalized remanent polarization value. 2 to 4 show values obtained by dividing each residual polarization value by the residual polarization value when a voltage of 6 V is applied to the ferroelectric capacitor. According to FIG. 2, the characteristics of those washed with n-butanol were superior to those of those not washed. In particular, what was washed before crystallization of the PZTN film showed the best characteristics. Specifically, the characteristic improvement was remarkable when the applied voltage was 1.8V.

  FIG. 3 is a diagram showing the saturation of the remanent polarization value of a ferroelectric capacitor manufactured using n-octanol as the cleaning liquid. In FIG. 3, the horizontal axis represents the applied voltage value, and the vertical axis represents the normalized remanent polarization value. According to FIG. 3, the characteristics of those washed with n-octanol were superior to those of those not washed. In particular, what was washed before crystallization of the PZTN film showed the best characteristics. Specifically, the characteristic improvement was remarkable when the applied voltage was 1.8V.

  FIG. 4 is a diagram showing the saturation of the remanent polarization value of a ferroelectric capacitor manufactured using 2-ethylhexanoic acid as a cleaning liquid. In FIG. 4, the horizontal axis represents the applied voltage value, and the vertical axis represents the normalized remanent polarization value. According to FIG. 4, both of the cleaning before crystallization and the cleaning after crystallization performed worse than the characteristics of those that were not cleaned. In particular, the characteristics deteriorated most when washing before crystallization was performed. This is presumably because 2-ethylhexanoic acid has acidity and a property of melting the ferroelectric film. Specifically, the characteristic improvement was remarkable when the applied voltage was 1.8V.

  From the above results, it was confirmed that cleaning with alcohols cleans the interface between the ferroelectric film and the electrode, and it is possible to manufacture a ferroelectric capacitor that can be driven at a low voltage. It was done.

4.5. Experimental Examples 8-10
The manufacturing method of the ferroelectric capacitor according to Experimental Examples 8 to 10 is as follows.

  A silicon oxide film having a thickness of 400 nm was formed on the surface of the silicon substrate by thermal oxidation. A titanium film was formed on the silicon oxide film by DC sputtering, and a titanium oxide film layer having a thickness of 40 nm was formed by thermal oxidation. A first platinum film having a thickness of 200 nm was formed on the titanium oxide film by ion sputtering and vapor deposition. Next, a PZTN precursor was formed by spin coating and degreased at 300 ° C. to form an amorphous PZTN film.

  Next, the surface of PZTN was washed with ozone water. The concentration of ozone water and the cleaning time are as shown in Table 2.

  Next, crystallization was performed by lamp heating at 650 ° C. for 5 minutes to form a PZTN film layer having a thickness of 100 nm.

  Next, a second platinum film having a thickness of 100 nm was formed on the PZTN film by DC sputtering using a metal mask. Next, the PZTN film was recovered by lamp heating at 650 ° C. for 5 minutes.

  A ferroelectric capacitor was manufactured by the above process.

4.6. Experimental Example 11
The manufacturing method of the ferroelectric capacitor according to Experimental Example 11 is as follows.

  A silicon oxide film having a thickness of 400 nm was formed on the surface of the silicon substrate by thermal oxidation. A titanium film was formed on the silicon oxide film by DC sputtering, and a titanium oxide film layer having a thickness of 40 nm was formed by thermal oxidation. A first platinum film having a thickness of 200 nm was formed on the titanium oxide film by ion sputtering and vapor deposition. Next, a PZTN precursor was formed by spin coating and degreased at 300 ° C. to form an amorphous PZTN film.

  Next, crystallization was performed by lamp heating at 650 ° C. for 5 minutes to form a PZTN film layer having a thickness of 100 nm.

  Next, a second platinum film having a thickness of 100 nm was formed on the PZTN film by DC sputtering using a metal mask. Next, the PZTN film was recovered by lamp heating at 650 ° C. for 5 minutes.

  A ferroelectric capacitor was manufactured by the above process.

4.7. Evaluation 2
The ferroelectric films obtained in Experimental Examples 8 to 11 were evaluated. The evaluation was performed on the saturation characteristic of the remanent polarization value of the ferroelectric capacitor. Table 2 shows an outline of the results of the concentration, cleaning time, and saturation characteristics of each ozone water used in Experimental Examples 8-11. In the characteristic column of Table 2, ◎ indicates that the characteristic was the best, ◯ indicates that the characteristic was good, and Δ indicates the characteristic as a reference.

  FIG. 5 is a diagram showing the saturation of the residual polarization value of a ferroelectric capacitor manufactured using ozone water as the cleaning liquid. In FIG. 5, the horizontal axis is the applied voltage value, and the vertical axis is the normalized remanent polarization value. FIG. 5 shows a value obtained by dividing each residual polarization value by the residual polarization value when a voltage of 6 V is applied to the ferroelectric capacitor. According to FIG. 5, the characteristics of those washed with ozone water were superior to those of those not washed. In particular, the characteristics of those washed with ozone water having an ozone concentration of 145 ppm were the best, followed by the characteristics of the capacitor according to Experimental Example 8 having an ozone concentration of 80 ppm and a washing time of 3 minutes. Specifically, the characteristic improvement was remarkable when the applied voltage was 1.8V.

5. Application Example Next, an example of a ferroelectric memory including the ferroelectric capacitor according to the present embodiment will be described. FIG. 6 is a cross-sectional view for explaining a ferroelectric memory according to an application example.

  As shown in FIG. 6, a MOS transistor 118 is formed on a silicon substrate 110 which is a semiconductor layer. An example of this process is described below. First, an element isolation film 116 for limiting an active region is formed on the silicon substrate 110. Next, a gate oxide film 111 is formed in the defined active region. A gate electrode 113 is formed on the gate oxide film 111, a sidewall 115 is formed on the side wall of the gate electrode 113, and impurity regions 117 and 119 serving as a source and a drain are formed on the silicon substrate 110 located in the element region. To do. In this way, the MOS transistor 118 is formed on the silicon substrate 110.

  Next, a first interlayer insulating film 126 containing silicon oxide as a main component is formed on the MOS transistor 118, and contact holes connected to the impurity regions 117 and 119 are formed in the first interlayer insulating film 126. To do. Here, only the contact hole connected to the impurity region 119 is illustrated. An adhesion layer (not shown) and a W plug 122 are embedded in these contact holes. Next, the ferroelectric capacitor 100 connected to the W plug 122 is formed on the first interlayer insulating film 126.

  The ferroelectric capacitor 100 has a structure in which a lower electrode 20, a ferroelectric film 30, and an upper electrode 40 are laminated in this order. The method for forming the ferroelectric capacitor 100 is as described above. Next, a second interlayer insulating film 140 containing silicon oxide as a main component is formed on the ferroelectric capacitor 100, and a via hole located on the ferroelectric capacitor 100 is formed. An adhesion layer and a W plug 132 connected to the ferroelectric capacitor 100 are embedded in the via hole. An Al alloy wiring 130 connected to the W plug 132 is formed on the second interlayer insulating film 140. Thereafter, a passivation film 142 is formed on the second interlayer insulating film 140 and the Al alloy wiring 130.

  The present invention includes substantially the same configuration (for example, a configuration having the same function, method, and result, or a configuration having the same purpose and result) as the configuration described in the embodiment. In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that achieves the same effect as the configuration described in the embodiment or a configuration that can achieve the same object. Further, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

1 is a cross-sectional view schematically showing a ferroelectric capacitor 100 according to the present embodiment. The figure which shows the saturation characteristic of the residual polarization amount of the ferroelectric capacitor concerning an experiment example. The figure which shows the saturation characteristic of the residual polarization amount of the ferroelectric capacitor concerning an experiment example. The figure which shows the saturation characteristic of the residual polarization amount of the ferroelectric capacitor concerning an experiment example. The figure which shows the saturation characteristic of the residual polarization amount of the ferroelectric capacitor concerning an experiment example. The figure which shows the example of application of the ferroelectric capacitor concerning this Embodiment.

Explanation of symbols

10 substrate, 12 TiAlN film, 20 first electrode, 22 first iridium film, 24 first iridium oxide film, 26 first platinum film, 30 ferroelectric film, 40 second electrode, 42 second platinum Film, 44 second iridium oxide film, 46 second iridium film, 100 ferroelectric capacitor, 110 silicon substrate, 111 gate oxide film, 113 gate electrode, 115 sidewall, 116 element isolation film, 117 impurity region, 118 MOS transistor, 119 impurity region, 122 W plug, 126 first interlayer insulating film, 130 Al alloy wiring, 132 W plug, 140 second interlayer insulating film, 142 passivation film 142

Claims (10)

(A) forming a ferroelectric film above the substrate;
(B) cleaning the surface of the ferroelectric film using ozone or an organic liquid that has a pKa> 7 and does not contain a metal element;
(C) forming a metal layer above the ferroelectric film;
A method for manufacturing a ferroelectric element, comprising: In claim 1,
A method for manufacturing a ferroelectric element, further comprising a step of performing a heat treatment for crystallizing the ferroelectric film between the steps (b) and (c). In claim 2,
Between the step of performing the heat treatment and the step (c),
A method for manufacturing a ferroelectric element, further comprising the step of cleaning the surface of the ferroelectric film using ozone or an organic liquid that has pKa> 7 and does not contain a metal element. In any one of Claims 1 thru | or 3,
Between the steps (a) and (b),
A method for manufacturing a ferroelectric element, further comprising a step of performing a heat treatment for degreasing the ferroelectric film. In any of claims 1 to 4,
The method for manufacturing a ferroelectric element, wherein the organic liquid is a liquid containing alcohols. In claim 5,
The method for manufacturing a ferroelectric element, wherein the organic liquid contains an alcohol having 4 or more carbon atoms. In claim 6,
The method for manufacturing a ferroelectric element, wherein the organic liquid contains butanol or octanol. In any of claims 1 to 4,
The method for manufacturing a ferroelectric element, wherein the organic liquid is a liquid containing amines. In any of claims 1 to 4,
In the step (b), the surface of the ferroelectric film is cleaned using ozone water, the method for manufacturing a ferroelectric element. Forming a first electrode above the substrate;
Forming a ferroelectric film above the lower electrode;
Applying a heat treatment for degreasing the ferroelectric film;
Cleaning the surface of the ferroelectric film with ozone water, butanol or octanol;
Applying a heat treatment for crystallizing the ferroelectric film;
Forming an upper electrode above the ferroelectric film;
A method for manufacturing a ferroelectric element, comprising: